RahasNym is a system that provides unlinkability in digital identity transactions to prevent a user's different online accounts and activities from being linked together. It allows users to create accounts across multiple service providers using pseudonyms rather than actual identity information. RahasNym is simpler and more flexible than previous solutions while still providing features like accountability, authenticity, and non-shareability of identity information. It uses a protocol suite and policy framework to enable unlinkable transactions with improved performance compared to existing approaches.

1. 1. Linkability Problem 2. Cost of the Linkability Problem
3. Existing Solutions and Positioning of Ours 4. RahasNym in Online Shopping
5. Architecture and Performance 6. Features, Benefits and Future Work
Digital identity is linked across many
identity providers and identity consumers.
SSN Authority
Issues:
Records: Passport No.
Mobile Network
Issues:
Records:
Email Provider
Issues:
Records:
Attack On Mat Honan’s
Connected Identity
Sometimes, it may cost your entire digital life!
deleted
Existing
transaction
systems
 Allows to create accounts
with pseudonyms
 Same identity information
enables linkability.
Solutions by
Previous
Research
 Lacks certain other desirable
features: e.g: accountability,
authenticity, non-shareability.
 More than three parties are
involved, bulky tokens,
complex protocols.
 Provides unconditional
unlinkability.
D. Chaum ‘85,
J. Camenish ‘01
RahasNym
 Simple, flexible and easily adoptable.
 Trades-off unconditional assurance to
achieve the right balance of desirable
features.
RahasNym: Preventing Linkability in the
Digital Identity Eco System
Request policy
CCN-IDT + non-interactive
ZKP with signature
User Device
Protocol 1 Protocol 2 Protocol 3 Protocol 4
Execution Time (ms) 2.945 84.257 82.148 148.48
Communication Size
(KB)
3.5 3.5 3.5 3.6
Service
Provider
IDP
internet
1
User
policy
SP
policy
Email-IDT, Addr-IDT
+ non-interactive ZKP
Transaction receipt
Email-
IDT
CCN
IDT
Address IDT
Main Components in RahasNym:
 Protocol Suite:
 IDT request protocol
 Three identity proof
protocols
 Policy Framework:
 Policy language, schema
 Policy combining
algorithm
Web App.
Client API
Native App.
Client API
IDM
Module
internet
internet
SP API
IDP API
5
2 4
2 4
1 5
3
- Four APIs exposed by
RahasNym.
RahasNym
Features
Future Work
Benefits for User
Benefits for IDP
Benefits for SP
• Unlinkability
• Accountability
• Confidentiality
• Authenticity
• Ownership Assurance
• Non-shareability
• Flexibility
• Ability to carry out
secure and unlinkable
transactions.
• Not having to maintain
identity repositories of users
which are targets of attackers.
• Provides accountability and
authenticity assurance on
transactions.
• Strong ownership
assurance on IDTs and
authenticity assurance
on transactions will
lower the costs caused
by frauds.
• Improving RahasNym to
facilitate re-use of IDTs while
at the same time preserving all
the desirable features.
Authors: Hasini Gunasinghe, Elisa Bertino
Shipping Service
Records:
Online Merchant
Records:
Bank
Issues:
Records: ,
Insurance Provider
Issues:
Records:
Healthcare Provider
Records: ,
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2
4 4
3